### Challenging questions for A Level Physics

These are some challenging questions that may potentially appear in the forthcoming A Level physics examination:

1) Two masses of 10kg each, are attached to a spring balance that is       calibrated in kg

 Spring balance

What is the reading of the spring balance, m,  if the system is in balance?

2) A boat of length 5m is moored close to the shore. A man walks       from the near-end to the far-end of the boat as shown below at 12m/s. The masses of the man and the boat are 50kg and 200kg  respectively.

How far has the boat moved from the shore, when the man reached the far-end of the boat?
Assume there is no friction between the boat and water and water remains stationary during the motion of the boat and the man.

3) Two objects are attached to a string and they are dropped from the      top of a tower with the string remaining slack.

What would be the tension of the string in the absence of drag or air resistance?

4) A balloon filled with air and a light plank float on the surface of a      large lake.

Both were taken into the lake to a certain depth and then released. What would be the subsequent motion of the plank and the balloon?